The present invention relates to an image forming device, and more particularly to an image forming device used in combination with a personal computer, for coloring by pressure development, after a latent image has been formed by exposure based on image information, a photosensitive recording medium capable of forming a latent image by exposure and comprising a plurality of microcapsules, that undergo a change of strength when irradiated with light of a predetermined wavelength, encapsulating a coloring material.
Image forming systems are known according to U.S. Pat. Nos. 4,440,846 and 4,399,209 wherein a photosensitive recording medium having a photosensitive layer including microcapsules comprising photosensitive material and encapsulating a coloring material is colored by pressure development after exposure to radiation based on image information. The microcapsules, whose mechanical strength changes when exposed to light, are ruptured by means of pressure development, whereupon the coloring material and other substances encapsulated in the microcapsules flow out and development occurs. An image forming color developing material, such as a substantially colorless color former, is typically encapsulated in the microcapsules, and when the microcapsules rupture, the color former reacts as coloring material with the developer material and coloring occurs.
In the image forming systems of the patents mentioned before, by passing the exposed photosensitive recording medium between a pair of an upper and a lower nip roller during pressure development, the microcapsules that were not photocured and those that were photo-softened are ruptured, whereupon development occurs. Moreover, in U.S. Pat. No. 4,648,699 a development technique is described which, instead of the pair of nip rollers, uses a point contact ball moving relative to the photosensitive recording medium.
U.S. Pat. No. 4,740,809 further discloses an image forming device for exposure by selectively guiding a white light emitted from a white light source across a photosensitive recording medium according to a printing pattern. The U.S. Pat. No. 4,740,809 also discloses an image forming device for exposure by guiding a light from a light source for a plurality of colors across a photosensitive recording medium. And U.S. Pat. No. 4,992,822 discloses an image forming device for repeatedly exposing the same pixels in a photosensitive recording medium capable of producing a plurality of color s via a polygonal mirror, respectively.
Next, the photo and pressure sensitive printer that can be inferred from the photo and pressure type image forming devices (called "photo and pressure sensitive printer" hereafter) disclosed in the plurality of patents will be explained.
The photo and pressure sensitive printer 200 shown in FIG. 19 comprises a printer housing 201, a lightproof cartridge 203, for accommodating photosensitive recording media 202, mounted to the front of the printer housing 201 so as to be easily detachable, a feed mechanism including a feed roller 204, a transport path 206 for transporting the photosensitive recording medium in a predominantly straight line from the feed roller 204 to the discharge roller 205, transport rollers 207 and a discharge roller 205 of the transport path 206, a preheating device 208 for preheating the photosensitive recording medium 202, an exposure mechanism 209 (including guide rods 210, a carriage 211 and an exposure head 211a) for exposing, while scanning in a direction perpendicular to the surface of the drawing, the transported photosensitive recording medium 202, a developing mechanism 212 for pressure development by means of a pair of an upper and a lower nip roller 214 and 215 including a roller maintained under pressure by a spring 213, a fixing heater 216 for heat-fixing the developed photosensitive recording medium 202, a discharge tray 217 provided at the rear end of the printer housing 201, etc.
The photo and pressure sensitive printer 220 shown in FIG. 20 is designed so that sheets are both fed and discharged at the front side of the printer housing 221. The printer 220 comprises a printer housing 221, a lightproof cartridge 223, for accommodating photosensitive recording media 222, mounted to the front of the printer housing 221 so as to be easily detachable, a feed mechanism including a feed roller 224, a transport path 225, whose side elevation is predominantly in the shape of the letter "U" lying on its side, for transporting the photosensitive recording medium 222 from the feed roller 224 to the discharge roller 229, transport rollers 226 to 228 and a discharge roller 229 of the transport path 225, a preheating device 230 for preheating the photosensitive recording medium 222, an exposure mechanism 231 (including guide rods 232, a carriage 233 and an exposure head 234) for exposing, while scanning in a direction perpendicular to the surface of the drawing, the transported photosensitive recording medium 222, a developing mechanism 235 for pressure development by means of a pair of an upper and a lower nip roller 238 and 237 including a roller maintained under pressure by a spring 236, a fixing heater 239 for heat-fixing the developed photosensitive recording medium 222, a discharge tray 240 provided at the rear end of the printer housing 221, etc.
When attempting to integrate one of the photo and pressure sensitive printers into a standard-sized open front storage bay of the tower enclosure for a personal computer (e.g. the 5 inch bay: 149 mm wide, 42 mm high and 208 mm deep: 5.9.times.1.7.times.8.2 inches), the photo and pressure sensitive printer 200 shown in FIG. 19 cannot be used because of its discharge tray, which is projecting from the rear end of the printer housing. Moreover, with this printer the handling of the photosensitive recording media is made difficult, since it is supplied from the front of the printer and discharged at the rear end.
In this respect the photo and pressure sensitive printer 220 shown in FIG. 20 is more advantageous than the printer shown in FIG. 19, because the photosensitive recording media is both supplied and discharged at the front of the printer housing, however, since it is necessary to form a transport path for the photosensitive recording media in the shape of the letter "U" lying on its side, the overall height of the printer housing increases to a point where it becomes all but impossible to integrate the printer into the standard-sized storage bay of a personal computer. A further disadvantage is that the total length of the transport path for transporting the photosensitive recording media increases, which results in higher manufacturing costs because of the greater number of parts necessary for the transport mechanism.
Furthermore, the use of 2 heaters, one for preheating and the other for fixing, as in the photo and pressure sensitive printers previously described, has the disadvantage that manufacturing costs increase because of the greater number of heater parts and the added wiring.